Pulverulent material dispensing and mixing apparatus



PULVERULENT MATERIAL DISPENSING AND MIXING APPARATUS Filed Sept. 30, 1964 2 Sheets-Sheet 1 i a 26 Q Q Q l flw E/vraes 44 54 1908597854416 5 Y JOAI/VAM/KSO/V,

BMIDM W swweu May 17, 1966 J. F. MASON ETAL PULVERULENT MATERIAL DISPENSING AND MIXING APPARATUS 2 Sheets-Sheet 2 Filed Sept. 30, 1964 BY a DWI ATTORNEKS 3 251 583 PULVERULENT MATERIAL DISPENSING AND MIXING APPARATUS John F. Mason, Robert B. Emery, and A. J. Speegle, Duncan, Okla, assignors to Halliburton Company, Duncan, Okla, a corporation of Delaware Filed Sept. 30, 1964, Ser. No. 400,309

Claims. (Cl. 259-151) This invention relates to apparatus for dispensing and mixing pulverulent material, and more particularly, to portable apparatus for supplying fluidized pulverulent material in a uniform stream.

It has been conventional practice to store dry pulverulent material in a cylindrical tank having a vertical discharge pipe mounted centrally in the tank. The bottom of the storage tank is in the shape of a cone and the lower end of the discharge pipe is spaced above the apex of the cone, which is the lowest point in the tank. The material in the tank is fluidized by blowing air into the tank and through the material surrounding the lower end of the discharge pipe. The pressure differential between the interior of the tank and the interior of the discharge causes the fluidized material to flow into the discharge pipe. The material around the perimeter of the cone, which is not fluidized, tends to fall into the vacant space as the fluidized material at the center of the cone flows into the dis-charge pipe. In order to insure that substantially all of the material in the tank is discharged through the outlet pipe, it is necessary to have a relatively small cone angle, thereby providing a steep slope of the conical surface of the bottom of the tank. Substantially all of the material is conveyed by gravity down the sloping conical surface to the apex of the cone where it becomes fluidized and flows out of the discharge pipe.

The steep slope of the conical surface which is required to insure adequate emptying of the tank causes the tank to be tall and have a high'center of gravity when the tank is full. If the tank is to be mounted on a vehicle for transporting dry pulverulent material to various locations, the vehicle tends to be unstable, particularly when the tank is full, It is desirable, therefore, for the tank to have as low a center of gravity as possible. Since the conical bottom portion of the tank represents a considerable waste of space in relation to the height of the tank, it is desirable to have as large a cone angle as possible, thereby minimizing the overall height of the tank. However, it has been found to be impractical to enlarge the cone angle of the tank because the material at the pevriphery of the cone tends to become caked, and if the matic tank systems is that the material in the tank tends to fall toward the center of the tank at a non-uniform rate and consequently the flow of fluidized material through the discharge pipe is non-uniform. There are sudden surges of fluidized pulverulent material through the discharge pipe, followed by comparatively sparse material flow. This surging action makes it impossible to regulate the rate of flow of fluidized material fro-m the tank and it is usually necessary to provide a surge tank in the discharge line to produce a more uniform flow of material through the discharge line.

In one important application of these material storage tanks, they are mounted on vehicles for transporting cement to a well site where the cement is mixed with water to form a cement slurry for cementing the well. Since it is necessary to transport the tank and its associated equipment from one well site to another, it is important Patented .May 17, 1966 ice -\out the complex valve and surge tank apparatus which is conventionally employed.

Accordingly, it is an object of this invent-ion to provide improved apparatus for storing and dispensing dry pulverulent material to overcome the deficiencies of the prior art as described above.

It is another object of this invention to provide an efiicient and economical system for dispensing dry pulverulent material from a storage tank directly to a water jet mixer.

It is a further object of this invention to provide a pneumatic dispensing tank which has a low center of gravity, and yet is effective in discharging substantially all of its contents.

These objects are accomplished in accordance with a preferred embodiment of the invention by a system for supplying fluidized pulverulent material directly to a conventional jet mixer including a pneumatic tank having a conical bottom in which the cone angle of the bottom is relatively large, so that the bottom surface has a low slope. The conical surface is in the form of a false bot tom which is air permeable, but impervious to the pulverulent material in the tank. An air distribution manifold under the false conical bottom supplies air uniformly around the conical surface and directs it towards the center of the apex. The manifold has a plurality of baffles which support the air permeable surface and channel the air toward the center of the apex to provide uniform air flow along the radius of the conical surface. A discharge pipe extends upright in the tank and the lower end of the pipe is spaced above the center of the bottom of the tank. A hose or tube connects the discharge pipe with the jet mixer and a valve is mounted in the hose to regulate the flow of material into the mixer. -As a result of the eificiency of the tank of this invention, the conical surface of the bottom may have a slope of as low as 4, and yet substantially all of the material in the tank is discharged, and is supplied to the jet mixer at a uniform rate.

This preferred embodiment of the invention is illustrated in the accompanying drawings in which:

FIG. 1 is a schematic view of the portable dispensing and mixing system of this invention, including a tank and a jet mixer;

, FIG. 2 is a cross sectional view of the tank along the line 22 in FIG. 1;

FIG. 3 is a cross sectional view of the tank along the line 33 in FIG. 2;

FIG. 4 is a cross sectional view of the bottom of the tank along the line 44- in FIG. 2;

FIG. 5 is a cross section-a1 view of the bottom of the tank along the line 5'5 in FIG. 2;

FIG. 6 is across sectional view of the tank along the line 66 in FIG. 2; and

FIG. 7 is a cross sectional view of the tank along the line 7-7 in FIG. 2. g

One important use for the system of this invention is in the dispensing of dry cement from a storage tank and mixing it with water to form a cement slurry. As shown in FIG. 1, a tank- 2 is mounted on a transport vehicle 4, which is shown schematically. Since the cement is discharged through the side of the tank, rather than through the bottom, the tank may be mounted lower on the vehicle than its position shown in FIG. 1. A discharge pipe 6, which is supported in the tank by conventional hangers, not shown, or other suitable means, extends upright in the tank and radially outward through the side of the tank. The rate of flow of the dry pulverulent material out of the tank may be adjusted by a valve 8. A cement and water mixing device, as shown schematically at 10, is located adjacent the tank 2 and a conduit 12 is connected to the discharge pipe 6 and conducts the material to the mixing'device 10. The mixer 18 is a conventional water jet mixer, an example of which is described in Patent No. 2,147,053. Water is supplied through the pipe 14 to the mixer where it is mixed with the cement powder to form a slurry which flows out of the pipe 16 to a sump 17 from which it is pumped into the well.

As shown in FIGS. 2 and 3, the tank of this invention has a cylindrical side wall 18, and a conical bottom 20 which is secured along its peripheral edge to the side wall 18. The top of the tank is enclosed by a cover 22, which is secured to the side wall 18.

Inside the tank, there is a false bottom. The false bottom includes a sloping deflector plate 24 which is frustoconical and secured along its outer edge to the side wall 1 8. The center portion of the false bottom has a frame 26 supporting a plurality of porous and permeable plates 28. The plates 28 are secured to the inner edge of the deflector 24. At the center of the bottom 20 there is a circular opening which is covered by a non-porous plate 30 and the discharge pipe 6 has its lower end spaced above the plate 30. An inlet pipe 32 for air or gas extends through the side wall 18 of the tank between the deflector 24 and the bottom 20. The deflector 24, the plates 28 and the bottom 20 form an enclosure for receiving the air from the pipe 32.

The material from which the plates 28 are formed is sufficiently rigid to be supported on the frame 26 and preferably is a porous and permeable plastic material, such as commercially available, porous and permeable, high density polyethylene. The pore size of this material is sufficiently large to allow a flow of air or gas there.- through, but not so large as to allow fine, particulate materal, such as powdered cement, to pass through the plates 28. The porous and permeable material has a permeability greater than 10 cubic feet of air per minute, and preferably 10 to cubic feet of air per minute per square foot of surface area, at a pressure differential across the material of approximately 2 inches of water.

The plates 28 are supported on the frame 26 which is arranged in'the pattern shown in' FIG. 2. In order to provide a uniform distribution of air from the annular chamberbetween the deflector 24 and the bottom into the region under the porous material 28, the frame 26 is in the form of a plurality of ribs or 'baflies and the plates 28 are supported on the ribs. A plurality of ribs 34 extend radially from the center of the tank bottom. The radial ribs 34 are secured by welding or other suitable means to a circular ring 36 which is mounted on the bottom 20 and supports the inner edge of the deflector 24, as shown in FIGS. 3 and 4. The inner end of each of the radial ribs 34 is secured by welding or other suitable means to a collar 38, as shown in FIGS. 3 and 7. The ribs 34 divide the space under the material 28 into quadrants and the ribs 34 prevent the flow of air between the quadrants, as shown in FIG. 5.

Intermediate ribs 40 extend inward-1y from the rings 36 and each has its opposite end secured to one of the radial ribs 34, except the central rib 40 in each quadrant which extends radially from the ring 36 to the collar 38. Each of the ribs 40 has a plurality of notches 42 spaced at intervals along the length of the rib to allow restricted air flow from one side of each rib 40 to theother. A ring of bridging 44, as shown in FIGS. 2, 3 and 6, provides lateral support for the ribs 40 and 34, but notches 46- in the bridging 44 permit air to flow through the bridging 44,

as shown in FIG. 6. The ring 36 also has a plurality of notches 48, as shown in FIG. 4, which are spaced at uniform intervals along the ring 36. The notches 46 and 48 in the bridging 44 and ring 36, respectively, permit air to flow from the space between the deflector 24 and the bottom 20 into the space under the plates 28.

As shown in FIGS. 4 to 7, the plates 28 are secured to the defletcor 24, the ribs 34 and 40, and the collar 38, respectively, by screws 50. Each plate 28 is formed of a separate sheet of porous material which covers each quadrant between the ribs 34, and the seam between adjacent plates 28 is rendered impervious by a sealing compound which is applied to the surface of the rib 34 and to the adjacent edges of the plates 28, as shown in FIG. 5. Similarly, the inner edge of the deflector 24 and the upper surfaces of the ribs 34 and the collar 38 are coated with a sealing compound before the screws 50 are applied to fasten the plates 28 to their'resepective supports.

The shape and arrangement of the ribs 34 and 4t), and the presence of the notched ring 36 and bridging 44 cause the air to be distributed uniformly under the plates 28, and rather than having a maximum rate of flow of air through the plates 28 in the region of the center of the bottom, the flow of air through the plates 28 is substantially uniform from the ring 36 to the collar 38. The space under the plates 28 on opposite sides of the central rib 40 of each quadrant extends from the ring 36 to the collar, except for the flow restriction of the bridging 44,

while along the radial edges of each quadrant, the spaces between the ribs 40 terminate at one of the radial impervious ribs 34. This arrangement prevents channelling of air to the zone of lowest pressure, which surrounds the discharge pipe 6, thereby providing a uniform flow of air. A uniform air flow pattern through the plates 28 efiiciently fluidizes the particles above the plates 28, and therefore, the material in the tank is conveyed out of the tank through the discharge pipe 6 with a minimum of air being supplied to the inlet pipe 32. It has been found that the structure of the tank bottom is so eflicient that the slope of the bottom 20 may be as low as four degrees and yet the slope is sufficient to direct the pulverulent material toward the center of the cone.

In operation, the tank of this invention, which preferably is mounted on a trailer, as shown schematically in FIG. 1, is transported to the well site and the discharge pipe 6 is connected with the hose 12 communicating with the jet mixer 10. The valve 8 in the pipe 6 regulates the rate of flow of cement through the discharge pipe 6 to the mixer 10. An air line is connected to the inlet pipe 32 and air under pressure is supplied to the space under the deflector 24. The rate of air flow may be adjusted to provide an adequate flow of air through the porous plates 28 to fluidize the particles above the plates. Due to the air flowing into the tank through the inlet pipe 32, the pressure in the tank is above atmospheric pressure. The current of air flowing upwardly through the plates 28 causes the particles to become fluidized and flow into the lower end of the discharge pipe 6. From the discharge pipe 6, the fluidized stream of particles flows to the hopper of the jet mixer 10. Suflicient water is supplied to the water inlet pipe 14 to mix with the powdered cement and form a cement slurry which flows out of the pipe 16.

The tank of thi invention is so efficient that it is possible to eliminate a surge tank which is usually required for separation of gas from the material before it is deposited in the mixing chamber of the jet mixer 10. The elimination of a surge tank allows material, such as dry cement, to be conveyed directly from the tank through a hose into the cement mixing device. The aerated pulverulent material behaves like a fluid and allows proportional mixing of two or more fluidized materials. The proportions of the fluidized materials which are mixed together can be controlled by varying the discharge rate from the storage tank 2 into the mixer. Elimination of the surge tank and other auxiliary equipment results in a saving in the amount of equipment required and yet provides increased versatility, particularly in mixing several pulverulent materials.

Another advantage of the efficient design of the tank of this invention is that the cone height may be relatively low, so that when mounted on a vehicle, the tank has a lower center of gravity than is possible with conventional tanks, which must have high cone height to operate properly.

While this invention has been illustrated and described in one embodiment, it is recognized that variations and changes may be made therein without departing from the invention as set forth in the claims,

We claim:

1. A storage tank for pulverulent material comprising a hollow receptacle having a circular bottom, a side wall and a top, said bottom sloping downwardly from the side wall toward the center of the bottom, means forming a chamber under the bottom and substantially coextensive therewith, said bottom including a circular impermeable plate at the center thereof and an impermeable deflector extending inwardly from the side wall toward the center of the plate and an air permeable plate extending between said deflector and said circular plate, said deflector being continuous around said side wall, said deflector having a greater slope than said permeable plate, a plurality of partitions extending radially in the chamber from the circular plate, a discharge pipe extending upright in the receptacle and extending out of the receptacle, the lower end of said pipe being spaced above the circular plate, and means for introducing air into the chamber, whereby pulverulent material may be fluidized and discharged from the receptacle.

2. A storage tank for pulverulent material comprising a hollow receptacle having a circular bottom, a side wall and a top, said bottom sloping downwardly from the side wall toward the center of the bottom, means forming a chamber under the bottom and substantially coextensive therewith, said bottom including a circular impermeable plate at the center thereof and an impermeable deflector extending inwardly from the side wall toward the center of the plate and an air permeable plate extending between said, deflector and said circular plate, said deflector being continuous around said side wall 'and forming a manifold between said chamber and said side wall, means for restricting the flow of air between said manifold and said chamber, a plurality of partitions extending radially in the chamber from the circular plate, a discharge pipe extending upright in the receptacle and extending out of the receptacle, the lower end of said pipe being spaced above the circular plate, and means for introducing air into the manifold, whereby the manifold distributes air to the chamber uniformly around the tank.

3. Apparatus for storing pulverulent material and for mixing cement comprising a storage tank having a bottom, I

, permeable surface sloping toward the center of the tank,

means forming a chamber under said permeable surface, means for introducing gas to said chamber, means in the chamber for distributing gas uniformly across said permeable surface, said discharge pipe extending upright in the center of said tank and the lower end of the pipe being spaced above said surface, and means for supplying gas under pressure to said chamber, said chamber being the only source of gas to the interior of the tank.

4. A storage tank for pulverulent material comprising a hollow receptacle having a circular bottom, a side wall and a top, said bottom sloping downwardly from the side wall toward the center of the bottom, means forming a chamber under the bottom and substantially coextensive therewith, a portion of said bottom being permeable to air but impermeable to pulverulent material, said permeable portion extending in sloping relation outwardly from adjacent the center of the bottom, means for conducting pulverulent material from adjacent the center of bottom to the exterior of the receptacle, a plurality of partitions in the chamber, said partitions extending under the permeable portion and having openings therein, a pair of said partitions extending toward the center of said bottom, and means for introducing air into said chamber substantially axially of said partitions from adjacent the outer edge of said permaeble bottom portion, whereby the flow of air through the permeable portion is substantially uniform.

5. A storage tank for pulverulent material comprising a hollow receptacle having a bottom, a side wall and a top, said bottom sloping downwardly from the side wall toward the center of the bottom, means forming a chamber under the bottom and substantially coextensive therewith, a portion of said bottom being permeable to air but impermeable to pulverulent material, means for introducing air to said chamber, said permeable portion extending in sloping relation outwardly from adjacent the center of the bottom, a discharge pipe, means for mounting said discharge pipe upright in the receptacle, the lower end of said pipe being spaced above the center of the-bottom, said bottom including an impermeable portion adjacent the discharge pipe, said bottom including a deflector portion extending between said side wall and said permeable portion, said deflector portion having a greater slope than said permeable portion, and means for diffusing air throughout the chamber whereby the flow extending inwardly from the side wall toward the center of the plate and an air permeable plate extending between said deflector and said circular plate, a plurality of partitions extending radially in the chamber from the circular plate, a discharge pipe extending upright in the receptacle and extending out of the receptacle, the lower end of said pipe being spaced above the circular plate, and means for introducing air into the chamber, whereby pulverulent material may be fluidized and discharged from the receptacle.

7. A storage tank according to claim 4 wherein the slope of the air permeable bottom portion is between 50 and 4. 1

, 8. A storage tank for pulverulent material comprising a hollow receptacle having a circular bottom, a side wall and a top, said bottom sloping downwardly from the side wall toward the center of the bottom, means forming a chamber under the bottom and substantially coextensive therewith, a portion of said bottom being permeable to air but impermeable to pulverulent material, means for introducing air to said chamber, said permeable portion extending substantially from a side wall to thecenter of the bottom, said chamber divided into a plurality of separate compartments adjacent the permaeble portion, saidbottom including an impermeable portion at the center thereof, each of said compartments having a pluraltiy of webs therein, means for securing said permeable portion of the bottom to said webs, at least one web in each compartment extending radially toward the impermeable portion ofsaid bottom, and at least one web in each compartment being parallel to the radial web, whereby a duct is provided in each compartment for distributing air uniformly within the compartments.

comprising 9. Apparatus for storing pulverulent material and for mixing cement comprising a storage tank having a bottom, top and sidewall forming a closed receptacle, a discharge pipe extending into said tank, a cement mixer conduit means connecting said discharge pipe and said mixer, said tank bottom including a chamber having a gas permeable surface adjacent the interior of the tank, said surface sloping toward the center of the tank, said discharge pipe extending upright in the center of said tank and the lower end of the pipe being spaced above said surface, and means for supplying gas under pressure to said cham ber, whereby the gas flows through the permeable surface fluidizing the pulverulent material to discharge the material through the pipe and into said mixer.

10. Apparatus for storing pulverulent material and for mixing cement comprising a storage tank having a bottom, top and sidewall forming a closed receptacle, a discharge pipe extending into said tank, a cement mixer, conduit means connecting said discharge pipe and said mixer, said tank bottom including a chamber having a gas permeable surface adjacent the interior of the tank, said surface sloping toward the center of the tank, said discharge pipe extending upright in. the center of said tank and the lower end of the pipe being spaced above said surface, means for supplying gas under pressure to said chamber, and means for controlling the rate of flow of pulverulent material through said discharge pipe, whereby the gas flows through the permeable surface fluidizing the pulverulent material to discharge the material through. the pipe and into said mixer and the rate of flow of material to the mixer may be adjusted.

References Cited by the Examiner UNITED STATES PATENTS 1,971,852 8/1934 Goebels 2594 2,835,482 4/1958 Stoughton 259-151 2,968,425 1/1961 Paton 222-195 3,096,968 7/1963 Kempthorne 259151 FOREIGN PATENTS 671,667 5/ 1952 Great Britain.

WALTER A. SCI-IEEL, Primary Examiner. ROBERT w. JENKINS, Assistant Examiner. 

9. APPARATUS FOR STORING PULVERULENT MATERIAL AND FOR MIXING CEMENT COMPRISING A STORAGE TANK HAVING A BOTTOM, TOP AND SIDEWALL FORMING A CLOSED RECEPTACLE, A DISCHARGE PIPE EXTENDING INTO SAID TANK, A CEMENT MIXER CONDUIT MEANS CONNECTING SAID DISCHARGE PIPE AND SAID MIXER, SAID TANK BOTTOM INCLUDING A CHAMBER HAVING A GAS PERMEABLE SURFACE ADJACENT THE INTERIOR OF THE TANK, SAID SURFACE SLOPIONG TOWARD THE CENTER OF THE TANK, SAID DISCHARGE PIPE EXTENDING UPRIGHT IN THE CENTER OF SAID TANK AND THE LOWER END OF THE PIPE BEING SPACED ABOVE SAID SURFACE, AND MEANS FOR SUPPLYING GAS UNDER PRESSURE TO SAID CHAMBER, WHEREBY THE GAS FLOWS THROUGH THE PERMEABLE SURFACE FLUIDIZING THE PULVERULENT MATERIAL TO DISCHARGE THE MATERIAL THROUGH THE PIPE AND INTO SAID MIXER. 